Subjects included in this study had participated in one of three randomized, double-blind, placebo-controlled smoking cessation clinical trials comparing varenicline, a nAChR partial agonist, with bupropion, a norepinephrine and dopamine reuptake inhibitor, and placebo (Box 1). The three trials have been described in detail previously (Gonzales et al, 2006; Jorenby et al, 2006; Oncken et al, 2006). In brief, all of the studies included a 12-week treatment period and 40-week non-treatment follow-up. Participants were healthy men and women; all had smoked an average of at least 10 cigarettes per day (CPD) during the past year, with no period of abstinence longer than 3 months, and were motivated to quit. For these clinical trials, patients were excluded if they had a history of alcohol or other drug abuse or dependence in the previous 12 months. Clinical trial endpoints included carbon monoxide-confirmed continuous abstinence from weeks 9 to 12 and weeks 9 to 52 (Gonzales et al, 2006; Jorenby et al, 2006; Oncken et al, 2006), and time to smoking relapse. Relapse to smoking after abstinence from weeks 9 to 12 was
